• The Journal of the Korean dental association
• /
• v.48 no.6
• /
• pp.469-477
• /
• 2010

The purpose of this study was to evaluate the effect of two dentin desensitizers and Er,Cr:YSGG laser for dentinal tubule occlusion. Twenty recently extracted single-rooted human teeth were used to obtain root dentinal fragments. The crowns were cut approximately 1mm below the cementum enamel junction(CEJ). A second cut was used to remove the apex of the root. Subsequently, a longitudinal cut was made in order to obtain 2 fragments from each root sample. The cementum from the cervical portion was removed using a high-speed diamond-coated bur in order to expose the dentin. To open dentinal tubules, forty samples were treated with 50% citric acid for 2 min and then rinsed under distilled water for 1 min. These were divided into four groups of ten samples each. The first group served as a control group. In group 2, the samples were irradiated with the Er,Cr:YSGG laser(Waterlase MD, Biolase, USA). In group 3, the samples were treated with Bisblock and ONE-STEP PLUS(Bisco, USA). In group 4, the samples were treated with Gluma comfort bond & Desensitizer(Heraeus Kulzer, Germany). All the samples were examined using Scanning electron microscopy(Hitachi, S-4700, Japan) with two different magnifications(X2000, X5000). These images were assessed by one examiner who was blind to the experimental procedure, using the index of smear layer removal. The distribution of smear layer removal grades was tested using Fisher's exact test. On the order hand, in order to evaluate the occluding effect of two dentin desensitizers and Er,Cr:YSGG laser, the number of exposed dentinal tubules was counted in each group. These were evaluated using the Kruskal-Wallis test with significance predetermined $\alpha$=0.05. There were statistically significant differences between the three groups(Er,Cr:YSGG laser, Bisblock+ONE-STEP PLUS, Gluma comfort bond & Desensitizer) and control group.

• Journal of the Korean association of regional geographers
• /
• v.22 no.1
• /
• pp.211-224
• /
• 2016

Natural lakes are estimated in variety with that's function or value depending on age environment or geographical characteristics. There are many kind of natural lakes, but the kind of natural lake is limited in rivers in korea flowing into East Sea. However, Yeonho lake in Uljin has different geographical characteristics with oxbow lake or lagoon which is common in korea's river flowing into East Sea. Therefore the purpose of this study is to analyze geographical characteristics due to the process of Yeonho's formation. Further more research for protecting wetland is needed to adequately preserve, depending on the geomorpologic process. To analyze geographical characteristics, it was essential to compare and analyze topographical map of 1918 1956 2012 and I pictured estinated line of bedrock and longitudinal section of Nam-dae cheon(Riv) Yeonho cheon(Riv). In addition, I denoted flooded areas through design flood level of Nam-dae cheon(Riv) Yeonho cheon(Riv) and analyzed particle size distribution of deposited sediment due to consider deposit environment. The results of study are as follows. In conclusion, Yeonho lake is floodbasin which was not researched at river flowing into East Sea. Through this study, my opinion is that floodbasin can be formed in the river that is steep and short. I argue that preservation methods will be seeked by geomorphologic process of floodbasin and development of downtown.

• Korean Journal of Plant Resources
• /
• v.33 no.6
• /
• pp.624-637
• /
• 2020

High-quality and high-phytonutrient watermelon fruits have strong market opportunities besides their health related benefits. Hence, investigating quality and nutritional related traits of watermelon genetic resources could provide important baseline data in breeding for increased lycopene content thereby increasing the marketability of watermelon. To this end, we have examined some fruit morphological traits and lycopene content of 105 genetic resources. Seeds, originally obtained from 22+ countries, were obtained from the National Agrobiodiversity Center, Jeonju, South Korea, grown in an experimental field and harvested at a fully mature stage. The size of pistil scar (SPS), the width of stripes (WS), weight of fruit (WF), length of fruit (LF), width of fruit (WIF), the thickness of pericarp (TP), soluble solids content (SSC), fruit shape in longitudinal section, ground color of skin, the intensity of the green color of skin, fruit shape at the apical part, grooving distribution, conspicuousness of stripes, and main color of the flesh were recorded on the field and inside laboratory and the lycopene was measured using spectrophotometric and HPLC methods. Watermelon fruits have shown a diverse morphological characters. Red and pink fleshed fruits dominated in the entire collections. Fruits with higher thickness of rind were found to exhibit less soluble solid content (SSC). Korean origin fruits were characterized by intermediate SSC while the United States of America (USA), Russia (RUS), Tajikistan (TJK), Turkmenistan (TKM), Taiwan (TWN), and Uruguay (URY) originated fruits had the highest SSC. The lycopene content varied between 41.37 and 182.82 ㎍/g, 2.81 and 163.72 ㎍/g, and 3.54 and 255.47 ㎍/g using HPLC, UV-Vis spectrophotometer, and microplate reader spectrophotometer, respectively. Red- and pink-fleshed fruits had the highest levels of lycopene content compared to the yellow- and orange-fleshed. Lycopene content had a significant positive correlation with SSC, however, no correlations were detected between lycopene and other quantitative fruit morphological characters. Our study demonstrated high diversity exists in fruit morphological traits and lycopene content of the germplasm collections which provide beneficial baseline data for a future breeding program and utilization of watermelon germplasm collections in gene banks for the maintenance and improvement of the current levels of production, marketability, and health-related benefit of watermelon fruits.

• Journal of Korea Water Resources Association
• /
• v.46 no.11
• /
• pp.1115-1128
• /
• 2013

The purpose of this study is to evaluate the suspended solids and eutrophication processes relationships in Chungju lake using CE-QUAL-W2, two-dimensional (2D) longitudinal/vertical hydrodynamic and water quality model. For water quality modeling, the lake segmentation was configured as 7 branches system according to their shape and tributary distribution. The model was calibrated (2010) and validated (2008) using 2 years of field data of water temperature, suspended solids (SS), total nitrogen (TN), total phosphorus (TP) and algae (Chl-a). The water temperature began to increase in depth from April and the stratification occurred at about 10 m early July heavy rain. The high SS concentration of the interflow density currents entering from the watershed was well simulated especially for July 2008 heavy rainfall event. The simulated concentration range of TN and TP was acceptable, but the errors might occur form the poor reflection for sedimentation velocity of nitrogen component and adsorption-sediment of phosphorus in model. The concentration of Chl-a was simulated well with the algal growth patterns in summer of 2010 and 2008, but the error of under estimation may come from the use of width-averaged velocity and concentration, not considering the actual to one side inclination by wind effect.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.34 no.7
• /
• pp.1109-1113
• /
• 2005

The objective of this study was to determine the effect of extrusion temperature on puffing of white and red ginseng powder. The extrusion variables were feed material (red and white ginseng powder) and die temperature $(100\;and\;115^{\circ}C)$. The analyzed characteristics of ginseng extrudates were sectional expansion index, microstructure and rheological properties. Most of biopolymer was highly puffed at higher extrusion temperature, but the cross-sectional expansion of white and red ginseng powder was higher at 1000e and longitudinal expansion seems to higher at $115^{\circ}C$. White and red ginseng powder were puffed inconsistently and discontinuously at $115^{\circ}C$. The scanning electron microphotograph of extruded white ginseng was uniform air cell distribution at 100oe, but pore size increased at $115^{\circ}C$ and had fine uniformity due to pore explosion. White ginseng and its extrudate were pseudoplastic. Intrinsic viscosity was lower as a result of increased die temperature. The cross-sectional expansion seems to be inconsistent and decreased due to decrease in melt viscosity at $115^{\circ}C$.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.33 no.2
• /
• pp.121-128
• /
• 2020

The purpose of this study is to investigate the distribution patterns of displacement and acceleration fields in a nonlinear soil ground based on the interaction of high-speed train, wheel, rail, and ground. For this purpose, a high-speed train in motion was modeled as the actual wheel, and the vertical contact of wheel and rail and the lateral contact, caused by meandering motion, were simulated; this simulation was based on the moving mass analysis. The soil ground part was given the nonlinear behavior of the upper ground part by using the modified the Drucker-Prager model, and the changes in displacement and acceleration were compared with the behavior of the elastic and inelastic grounds. Using this analysis, the displacement and acceleration ranges close to the actual ground behavior were addressed. Additionally, the von-Mises stress and equivalent plastic strain at the ground were examined. Further, the equivalent plastic and total volumetric strains at each failure surface were examined. The variation in stresses, such as vertical stress, transverse pressure, and longitudinal restraint pressure of wheel-rail contact, with the time history was investigated using moving mass. In the case of nonlinear ground model, the displacement difference obtained based on the train travel is not large when compared to that of the elastic ground model, while the acceleration is caused to generate a large decrease.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.31 no.3
• /
• pp.213-219
• /
• 1995

The author carried out an experiment to find out the response of Black porgy, Acanthopagrus schlegelii [Bleeker] to the color lights. The experimental tank ($360L{\times}50W{\times}55H$cm) was set up in a dark room. Six longitudinal sections with 60cm intervals are marked in the tank to observe the location of the fish. Water depth in the tank was kept 50cm level. Light bulbs of 20 W at the both ends of the tank projected the light horizontally into the tank. Two different colored filters were selected from four colors of red, blue, yellow, and white, and they were placed in front of the light bulbs to make different colors of light. Light intensity was controlled by use of auxiliary filters intercepted between the bulb and the filter. The fishes were acclimatized in the dark for 50 minutes before they were employed in the experiment. Upon turning on the light, the number of fish in each section was counted 40 times in 30 second intervals, and the mean of the number of fish in each section was given as the gathering rate of the fish. The colors favourited by the fish was found in order of blue, yellow, white and red in the day-time and blue, red, yellow and white at night. The difference of the average distribution on two different colors of light was 7.18%(0.35-19.55%), and the difference in the daytime(8.20%) was larger than at night (6.15%). The gathering rate of fish on illumination period didn't show the regular trend of increase and decrease, and was fluctuated with instability. The difference of the gathering rate on two different colors of light wasn't distinct, and the difference in the daytime was larger than at night.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.23 no.3
• /
• pp.27-27
• /
• 1987

The purpose of this study is to find the light intensity which induced maximum gathering rate and to observe the variation of the gathering rate both at daytime and night by using Sea-bass, Epinephelus septemfasciatus (Thunberg). An experimental tank (360 L×50 W×55H cm) was set up in a dark room. An illumination system was attached to the end of one side of the tank to control horizontal light intensity. Eight artificial light sources were prepared by combination of three with white light bulbs (10W, 60W, 100W) and eight filters. During the experiment water depth was maintained 50cm level in the tank. The tank was marked into six longitudinal sections each being 60cm long to observe the distribution of fish. The fish were acclimatized in dark condition for 50 minutes before the main experiment. Upon turning on the light, the number of fish in each section was counted 60 times every 30 seconds, and the gathering rate was obtained from the average number of fish in each section. The light intensity inducing maximum gathering rate was 24.13 lux (15.25~35.93 lux) at daytime and 0.41 lux (0.25~0.63 lux) at night. The variation of the gathering rate of fish in illumination time was great and did not show any definite pattern but fluctuated irregularly. Its different between daytime and night is remarkable.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.23 no.3
• /
• pp.137-143
• /
• 1987

The purpose of this study is to find the light intensity which induced maximum gathering rate and to observe the variation of the gathering rate both at daytime and night by using Sea-bass, Epinephelus septemfasciatus (Thunberg). An experimental tank (360 L$\times$50 W$\times$55H cm) was set up in a dark room. An illumination system was attached to the end of one side of the tank to control horizontal light intensity. Eight artificial light sources were prepared by combination of three with white light bulbs (10W, 60W, 100W) and eight filters. During the experiment water depth was maintained 50cm level in the tank. The tank was marked into six longitudinal sections each being 60cm long to observe the distribution of fish. The fish were acclimatized in dark condition for 50 minutes before the main experiment. Upon turning on the light, the number of fish in each section was counted 60 times every 30 seconds, and the gathering rate was obtained from the average number of fish in each section. The light intensity inducing maximum gathering rate was 24.13 lux (15.25~35.93 lux) at daytime and 0.41 lux (0.25~0.63 lux) at night. The variation of the gathering rate of fish in illumination time was great and did not show any definite pattern but fluctuated irregularly. Its different between daytime and night is remarkable.

• Korean Journal of Social Welfare Studies
• /
• v.49 no.3
• /
• pp.209-245
• /
• 2018

In this study, various performance types, the combinations of the performance types for growth were investigated to suggest viable policy recommendations for the sustainable growth of social enterprises. The data of the economic and social performance of social enterprises from 2011 to 2016 were obtained and the changes were investigated. Among total of 235 social enterprises that participated in Cho et al, 2011, the research subjects were 164 social enterprises, which were still being operated in March, 2018. The performance of 6 years, since 2011, was surveyed, and total of 104(recovery factor: 69.8%) of social enterprises were analyzed using the growth mixture model, cross tabulation. First of the results, the latent trajectory classes of sales, which are of economic performance, were investigated through the analysis of growth mixture model. The optimal model including three latent classes was adopted. The three latent classes were named as 'mature sales type', 'growing sales type', and 'average sales type'. Second, the latent trajectory classes of employment rate, which are of social performance, were investigated. The optimal model including three latent classes was adopted. The three latent classes were named as 'average employment type', 'declining employment type', and 'increasing employment type'. Third, cluster in $3{\times}3$ tabulation, which is a distribution of the latent trajectory classes of social performance based on the latent trajectory classes of economic performance of social enterprises, was looked into.